The present invention generally relates to a branch joint box for performing branching of a circuit through branch joint of connectors of wiring harness, etc. for a motor vehicle and more particularly, to a branch joint box including a lower casing and an upper casing, in which it is possible to easily judge whether or not the lower and upper casings have been locked to each other through fitting.
In a branch joint box used for joining a wiring harness, etc. for a motor vehicle to various electrical parts by branching, branch joint points are concentrated at one spot so as to reasonably and economically join a circuit by branching. In response to rise of densities of wires of the wiring harness, various types of branch joint boxes have been developed.
For example, as shown in FIG. 1, a known branch joint box includes a lower casing 1 and an upper casing 2. The lower and upper casings 1 and 2 are locked to each other through fitting, while upper and lower portions of the lower and upper casings 1 and 2 locked to each other through fitting are closed by upper and lower covers (not shown), respectively. In this known branch joint box, when an outer surface of an outer peripheral wall 2a of the upper casing 2 is fitted into an inner surface of an outer peripheral wall 1a of the lower casing 1, a locking projection 1b formed on the inner surface of the outer peripheral wall 1a of the lower casing 1 rides over a locking projection 2b formed on the outer surface of the outer peripheral wall 2a of the upper casing 2 so as to be carried to an upper side of the locking projection 2b as shown in FIGS. 3 and 4. Thus, the locking projection 1b of the lower casing 1 is brought into engagement with the locking projection 2b of the upper casing 2 such that the lower and upper casings 1 and 2 are locked to each other.
When the lower and upper casing 1 and 2 are locked to each other by fitting the upper casing 2 into the lower casing 1, the outer peripheral wall 1a of the lower casing 1 deflects through a height of the locking projection 1b, for example, 2 mm outwardly from the outer peripheral wall 2a of the upper casing 2 in an incomplete engagement state in which the locking projection 2b rides onto the locking projection 1b as shown in FIG. 5. From this deflection of the outer peripheral wall 1a of the lower casing 1, it is possible to judge that the locking projections 1b and 2b are in the incomplete engagement state.
However, prior to the incomplete engagement state, the outer peripheral wall 1a of the lower casing 1 does not deflect outwardly from the outer peripheral wall 2a of the upper casing 1. Meanwhile, in a complete engagement state, the locking projection 2b of the upper casing 2 is disposed under the locking projection 1b of the lower casing 1 as shown in FIG. 4. However, as shown in FIG. 2, the locking projection 2b disposed under the locking projection 1b in the complete engagement state has a width 12 equal to a width 11 of the locking projection 1b. Thus, even if the locking projection 1b of the outer peripheral wall 1a and the locking projection 2b of the outer peripheral wall 2a are visually inspected from above, it is difficult to judge whether the locking projections 1b and 2b are in the complete engagement state or the incomplete engagement state.